ABSTRACT
While hemodynamic stress plays a key role in aneurysm formation outside of SCD, its role is understudied in patients with SCD. We hypothesized that tissue-based markers of hemodynamic stress are associated with aneurysm presence in a prospective SCD cohort. Children and adults with SCD, with and without aneurysms, underwent longitudinal brain MRI/MRA to assess cerebral blood flow (CBF) and oxygen extraction fraction (OEF). Baseline characteristics were recorded. In the subgroup of adults, stepwise mixed-effect logistic regression examined clinical variables, CBF, and OEF as predictors of aneurysm presence. Cumulative rates of new aneurysm formation were estimated using Kaplan-Meier analyses. Forty-three aneurysms were found in 27 of 155 patients (17%). Most aneurysms were ≤ 3 mm and in the intracranial internal carotid artery. On univariate analysis, older age (p=0.07), lower hemoglobin (p=0.002), higher CBF (p=0.03), and higher OEF (p=0.02) were associated with aneurysm presence. On multivariable analysis, age and CBF remained independently associated with aneurysm presence. Seventy-six patients (49% of enrollment) received follow-up MRAs (median 3.5 years). No aneurysm grew or ruptured, however, seven new aneurysms developed in six patients. The three-year cumulative rate of aneurysm formation was 3.5%. In 155 patients with SCD, 17% had intracranial aneurysms. Three-year aneurysm formation rate was 3.5%, although limited by small longitudinal sample size and short follow-up duration. Aneurysm presence was associated with elevated CBF in adults, as a tissue-based marker of cerebral hemodynamic stress. Future studies may examine the predictive role of CBF in aneurysm development in SCD.
ABSTRACT
BackgroundRetinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a rare, autosomal dominant, universally fatal disease without effective treatment options. This study explores the safety and preliminary efficacy of crizanlizumab, a humanized monoclonal antibody against P-selectin approved for the prevention of sickle cell crises, in slowing retinal nonperfusion and preserving vision in patients with RVCL-S.METHODSEleven patients with RVCL-S with confirmed exonuclease 3 prime repair exonuclease 1 (TREX1) mutations received monthly crizanlizumab infusions over 2 years. The study measured the nonperfusion index within 3 retinal zones and the total retina with fluorescein angiography, visual acuity, intraocular pressure (IOP), and optical coherence tomography central subfield thickness (CST) at baseline, 1 year, and 2 years. A mixed repeated-measures analysis was performed to assess the progression rates and changes from baseline.RESULTSEleven participants received crizanlizumab infusions. All of the participants tolerated crizanlizumab well, with 8 of 11 (72.7%) reporting mild adverse effects such as nausea, fatigue, and gastrointestinal symptoms. The change in total retinal nonperfusion was 7.22% [4.47, 9.97] in year 1 and -0.69% [-4.06, 2.68] in year 2 (P < 0.001). In the mid periphery, the change in nonperfusion was 10.6% [5.1, 16.1] in year 1 and -0.68% [-3.98, 5.35] in year 2 (P < 0.01), demonstrating a reduction in progression of nonperfusion in the second year of treatment. Visual acuity, IOP, and CST remained stable.CONCLUSIONCrizanlizumab has an acceptable safety profile. These results show promising potential for examining crizanlizumab in larger studies of RVCL-S and similar small-vessel diseases and for using the retina as a biomarker for systemic disease.Trial registrationClinicalTrials.gov NCT04611880.FUNDINGThe Clayco Foundation; DeNardo Education and Research Foundation Grant; Jeffrey T. Fort Innovation Fund; Siteman Retina Research Fund; unrestricted grant from Research to Prevent Blindness Inc.; National Heart,Lung, and Blood Institute (NHLBI), NIH (R01HL129241); National Institute of Neurological Disorders and Stroke (NINDS), NIH (RF1NS116565).
Subject(s)
Antibodies, Monoclonal, Humanized , Humans , Male , Female , Adult , Antibodies, Monoclonal, Humanized/therapeutic use , Antibodies, Monoclonal, Humanized/adverse effects , Antibodies, Monoclonal, Humanized/administration & dosage , Middle Aged , Leukoencephalopathies/drug therapy , Exodeoxyribonucleases/genetics , Retinal Diseases/drug therapy , PhosphoproteinsABSTRACT
BACKGROUND: Most adults with sickle cell disease will experience a silent cerebral infarction (SCI) or overt stroke. Identifying patient subgroups with increased stroke incidence is important for future clinical trials focused on stroke prevention. Our 3-center prospective cohort study tested the primary hypothesis that adults with sickle cell disease and SCIs have a greater incidence of new stroke or SCI compared with those without SCI. A secondary aim focused on identifying additional risk factors for progressive infarcts, particularly traditional risk factors for stroke in adults. METHODS AND RESULTS: This observational study included adults with sickle cell disease and no history of stroke. Magnetic resonance imaging scans of the brain completed at baseline and >1 year later were reviewed by 3 radiologists for baseline SCIs and new or progressive infarcts on follow-up magnetic resonance imaging. Stroke risk factors were abstracted from the medical chart. Time-to-event analysis was utilized for progressive infarcts. Median age was 24.1 years; 45.3% of 95 participants had SCIs on baseline magnetic resonance imaging. Progressive infarcts were present in 17 participants (17.9%), and the median follow-up was 2.1 years. Incidence of new infarcts was 11.95 per 100 patient-years (6.17-20.88) versus 3.74 per 100 patient-years (1.21-8.73) in those with versus without prior SCI. Multivariable Cox regression showed that baseline SCI predicts progressive infarcts (hazard ratio, 3.46 [95% CI, 1.05-11.39]; P=0.041); baseline hypertension was also associated with progressive infarcts (hazard ratio, 3.23 [95% CI, 1.16-9.51]; P=0.025). CONCLUSIONS: Selecting individuals with SCIs and hypertension for stroke prevention trials in sickle cell disease may enrich the study population with those at highest risk for infarct recurrence.
Subject(s)
Anemia, Sickle Cell , Cerebral Infarction , Magnetic Resonance Imaging , Recurrence , Humans , Anemia, Sickle Cell/complications , Anemia, Sickle Cell/epidemiology , Anemia, Sickle Cell/diagnosis , Incidence , Female , Male , Risk Factors , Adult , Prospective Studies , Young Adult , Cerebral Infarction/epidemiology , Cerebral Infarction/etiology , Cerebral Infarction/diagnostic imaging , Stroke/epidemiology , Stroke/etiology , Stroke/prevention & control , Disease Progression , Time Factors , Adolescent , Hypertension/epidemiology , Hypertension/complications , Risk AssessmentABSTRACT
BACKGROUND AND OBJECTIVES: People with sickle cell disease (SCD) are at risk of cognitive dysfunction independent of stroke. Diminished functional connectivity in select large-scale networks and white matter integrity reflect the neurologic consequences of SCD. Because chronic transfusion therapy is neuroprotective in preventing stroke and strengthening executive function abilities in people with SCD, we hypothesized that red blood cell (RBC) transfusion facilitates the acute reversal of disruptions in functional connectivity while white matter integrity remains unaffected. METHODS: Children with SCD receiving chronic transfusion therapy underwent a brain MRI measuring white matter integrity with diffusion tensor imaging and resting-state functional connectivity within 3 days before and after transfusion of RBCs. Cognitive assessments with the NIH Toolbox were acquired after transfusion and then immediately before the following transfusion cycle. RESULTS: Sixteen children with a median age of 12.5 years were included. Global assessments of functional connectivity using homotopy (p = 0.234) or modularity (p = 0.796) did not differ with transfusion. Functional connectivity within the frontoparietal network significantly strengthened after transfusion (median intranetwork Z-score 0.21 [0.17-0.30] before transfusion, 0.29 [0.20-0.36] after transfusion, p < 0.001), while there was not a significant change seen within the sensory motor, visual, auditory, default mode, dorsal attention, or cingulo-opercular networks. Corresponding to the change within the frontoparietal network, there was a significant improvement in executive function abilities after transfusion (median executive function composite score 87.7 [81.3-90.7] before transfusion, 90.3 [84.3-93.7] after transfusion, p = 0.021). Participants with stronger connectivity in the frontoparietal network before transfusion had a significantly greater improvement in the executive function composite score with transfusion (r = 0.565, 95% CI 0.020-0.851, p = 0.044). While functional connectivity and executive abilities strengthened with transfusion, there was not a significant change in white matter integrity as assessed by fractional anisotropy and mean diffusivity within 16 white matter tracts or globally with tract-based spatial statistics. DISCUSSION: Strengthening of functional connectivity with concomitant improvement in executive function abilities with transfusion suggests that functional connectivity MRI could be used as a biomarker for acutely reversible neurocognitive injury as novel therapeutics are developed for people with SCD.
Subject(s)
Anemia, Sickle Cell , Cognitive Dysfunction , Diffusion Tensor Imaging , Humans , Anemia, Sickle Cell/therapy , Anemia, Sickle Cell/complications , Anemia, Sickle Cell/physiopathology , Male , Child , Female , Adolescent , Cognitive Dysfunction/etiology , Cognitive Dysfunction/therapy , Cognitive Dysfunction/physiopathology , Cognitive Dysfunction/diagnostic imaging , Erythrocyte Transfusion , Magnetic Resonance Imaging , Brain/diagnostic imaging , Brain/physiopathology , White Matter/diagnostic imaging , White Matter/pathology , Executive Function/physiology , Neural Pathways/physiopathology , Neural Pathways/diagnostic imagingABSTRACT
BACKGROUND AND OBJECTIVES: Previously we demonstrated that 90% of infarcts in children with sickle cell anemia occur in the border zone regions of cerebral blood flow (CBF). We tested the hypothesis that adults with sickle cell disease (SCD) have silent cerebral infarcts (SCIs) in the border zone regions, with a secondary hypothesis that older age and traditional stroke risk factors would be associated with infarct occurrence in regions outside the border zones. METHODS: Adults with SCD 18-50 years of age were enrolled in a cross-sectional study at 2 centers and completed a 3T brain MRI. Participants with a history of overt stroke were excluded. Infarct masks were manually delineated on T2-fluid-attenuated inversion-recovery MRI and registered to the Montreal Neurological Institute 152 brain atlas to generate an infarct heatmap. Border zone regions between anterior, middle, and posterior cerebral arteries (ACA, MCA, and PCA) were quantified using the Digital 3D Brain MRI Arterial Territories Atlas, and logistic regression was applied to identify relationships between infarct distribution, demographics, and stroke risk factors. RESULTS: Of 113 participants with SCD (median age 26.1 years, interquartile range [IQR] 21.6-31.4 years, 51% male), 56 (49.6%) had SCIs. Participants had a median of 5.5 infarcts (IQR 3.2-13.8). Analysis of infarct distribution showed that 350 of 644 infarcts (54.3%) were in 4 border zones of CBF and 294 (45.6%) were in non-border zone territories. More than 90% of infarcts were in 3 regions: the non-border zone ACA and MCA territories and the ACA-MCA border zone. Logistic regression showed that older participants have an increased chance of infarcts in the MCA territory (odds ratio [OR] 1.08; 95% CI 1.03-1.13; p = 0.001) and a decreased chance of infarcts in the ACA-MCA border zone (OR 0.94; 95% CI 0.90-0.97; p < 0.001). The presence of at least 1 stroke risk factor did not predict SCI location in any model. DISCUSSION: When compared with children with SCD, in adults with SCD, older age is associated with expanded zones of tissue infarction that stretch beyond the traditional border zones of CBF, with more than 45% of infarcts in non-border zone regions.
Subject(s)
Anemia, Sickle Cell , Cerebral Infarction , Magnetic Resonance Imaging , Humans , Anemia, Sickle Cell/complications , Anemia, Sickle Cell/diagnostic imaging , Anemia, Sickle Cell/epidemiology , Male , Female , Cerebral Infarction/diagnostic imaging , Cerebral Infarction/epidemiology , Cerebral Infarction/etiology , Adult , Young Adult , Cross-Sectional Studies , Middle Aged , Adolescent , Risk Factors , Brain/diagnostic imaging , Brain/pathology , Cerebrovascular Circulation/physiologyABSTRACT
Abnormal oxygen extraction fraction (OEF), a putative biomarker of cerebral metabolic stress, may indicate compromised oxygen delivery and ischemic vulnerability in patients with sickle cell disease (SCD). Elevated OEF was observed at the tissue level across the brain using an asymmetric spin echo (ASE) MR method, while variable global OEFs were found from the superior sagittal sinus (SSS) using a T2-relaxation-under-spin-tagging (TRUST) MRI method with different calibration models. In this study, we aimed to compare the average ASE-OEF in the SSS drainage territory and TRUST-OEF in the SSS from the same SCD patients and healthy controls. 74 participants (SCD: N = 49; controls: N = 25) underwent brain MRI. TRUST-OEF was quantified using the Lu-bovine, Bush-HbA and Li-Bush-HbS models. ASE-OEF and TRUST-OEF were significantly associated in healthy controls after controlling for hematocrit using the Lu-bovine or the Bush-HbA model. However, no association was found between ASE-OEF and TRUST-OEF in patients with SCD using either the Bush-HbA or the Li-Bush-HbS model. Plausible explanations include a discordance between spatially volume-averaged oxygenation brain tissue and flow-weighted volume-averaged oxygenation in SSS or sub-optimal calibration in SCD. Further work is needed to refine and validate non-invasive MR OEF measurements in SCD.
Subject(s)
Anemia, Sickle Cell , Brain , Magnetic Resonance Imaging , Oxygen , Humans , Male , Anemia, Sickle Cell/metabolism , Anemia, Sickle Cell/diagnostic imaging , Female , Adult , Oxygen/metabolism , Magnetic Resonance Imaging/methods , Brain/metabolism , Brain/diagnostic imaging , Cerebrovascular Circulation/physiology , Young Adult , Middle Aged , Superior Sagittal Sinus , Oxygen Consumption/physiology , Case-Control StudiesABSTRACT
BACKGROUND: Silent cerebral infarcts (SCI) in sickle cell anemia (SCA) are associated with future strokes and cognitive impairment, warranting early diagnosis and treatment. Detection of SCI, however, is limited by their small size, especially when neuroradiologists are unavailable. We hypothesized that deep learning may permit automated SCI detection in children and young adults with SCA as a tool to identify the presence and extent of SCI in clinical and research settings. METHODS: We utilized UNet-a deep learning model-for fully automated SCI segmentation. We trained and optimized UNet using brain magnetic resonance imaging from the SIT trial (Silent Infarct Transfusion). Neuroradiologists provided the ground truth for SCI diagnosis, while a vascular neurologist manually delineated SCI on fluid-attenuated inversion recovery and provided the ground truth for SCI segmentation. UNet was optimized for the highest spatial overlap between automatic and manual delineation (dice similarity coefficient). The optimized UNet was externally validated using an independent single-center prospective cohort of SCA participants. Model performance was evaluated through sensitivity and accuracy (%correct cases) for SCI diagnosis, dice similarity coefficient, intraclass correlation coefficient (metric of volumetric agreement), and Spearman correlation. RESULTS: The SIT trial (n=926; 31% with SCI; median age, 8.9 years) and external validation (n=80; 50% with SCI; age, 11.5 years) cohorts had small median lesion volumes of 0.40 and 0.25 mL, respectively. Compared with the neuroradiology diagnosis, UNet predicted SCI presence with 100% sensitivity and 74% accuracy. In magnetic resonance imaging with SCI, UNet reached a moderate spatial agreement (dice similarity coefficient, 0.48) and high volumetric agreement (intraclass correlation coefficient, 0.76; ρ=0.72; P<0.001) between automatic and manual segmentations. CONCLUSIONS: UNet, trained using a large pediatric SCA magnetic resonance imaging data set, sensitively detected small SCI in children and young adults with SCA. While additional training is needed, UNet may be integrated into the clinical workflow as a screening tool, aiding in SCI diagnosis.
Subject(s)
Anemia, Sickle Cell , Child , Humans , Young Adult , Prospective Studies , Anemia, Sickle Cell/complications , Anemia, Sickle Cell/diagnostic imaging , Anemia, Sickle Cell/therapy , Cerebral Infarction/complications , Brain , Magnetic Resonance ImagingABSTRACT
BACKGROUND: Alzheimer's disease (AD) and vascular contributions to cognitive impairment and dementia (VCID) pathologies coexist in patients with cognitive impairment. Abnormal amyloid beta (Aß) deposition is the hallmark pathologic biomarker for AD. Neuroinflammation may be a pathophysiological mechanism in both AD and VCID. In this study, we aimed to understand the role of neuroinflammation and Aß deposition in white matter hyperintensities (WMH) progression and cognitive decline over a decade in patients with mixed AD and VCID pathologies. METHODS: Twenty-four elderly participants (median [interquartile range] age 78 [64.8, 83] years old, 14 female) were recruited from the Knight Alzheimer Disease Research Center. 11C-PK11195 standard uptake value ratio (SUVR) and 11C-PiB mean cortical binding potential (MCBP) were used to evaluate neuroinflammation and Aß deposition in-vivo, respectively. Fluid-attenuated inversion recovery MR images were acquired to obtain baseline WMH volume and its progression over 11.5 years. Composite cognitive scores (global, processing speed and memory) were computed at baseline and follow-up over 7.5 years. Multiple linear regression models evaluated the association between PET biomarkers (11C-PK11195 SUVR and 11C-PiB MCBP) and baseline WMH volume and cognitive function. Moreover, linear mixed-effects models evaluated whether PET biomarkers predicted greater WMH progression or cognitive decline over a decade. RESULTS: Fifteen participants (62.5%) had mixed AD (positive PiB) and VCID (at least one vascular risk factor) pathologies. Elevated 11C-PK11195 SUVR, but not 11C-PiB MCBP, was associated with greater baseline WMH volume and predicted greater WMH progression. Elevated 11C-PiB MCBP was associated with baseline memory and global cognition. Elevated 11C-PK11195 SUVR and elevated 11C-PiB MCBP independently predicted greater global cognition and processing speed declines. No association was found between 11C-PK11195 SUVR and 11C-PiB MCBP. CONCLUSIONS: Neuroinflammation and Aß deposition may represent two distinct pathophysiological pathways, and both independently contributed to the progression of cognitive impairment in mixed AD and VCID pathologies. Neuroinflammation, but not Aß deposition, contributed to WMH volume and progression.
Subject(s)
Alzheimer Disease , Cognitive Dysfunction , Dementia, Vascular , Humans , Female , Aged , Aged, 80 and over , Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Dementia, Vascular/diagnostic imaging , Neuroinflammatory Diseases , Cognitive Dysfunction/diagnostic imaging , Cognitive Dysfunction/etiology , Cognitive Dysfunction/pathology , Biomarkers , Positron-Emission TomographyABSTRACT
Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a rare autosomal dominant disease resulting from a frame-shift mutation in TREX1, an intracellular 3'-5' exonuclease 1. Hepatic findings include an elevated alkaline phosphatase (ALP) and nodular regenerative hyperplasia (NRH). Affected individuals typically succumb to brain lesions before clinically apparent hepatic manifestations; thus, little else is known about the hepatic pathology. Autopsy reports and a liver section from each (n = 11) of three unrelated kindreds with the most common mutation in TREX1 (V235Gfs∗6) were studied with standard and immunohistochemical stains. Cases were compared with "normal liver" controls from similar autopsy years. Cases consisted of six men and five women who died at a median age of 50 yr (range, 41-60 yr.). Seven had elevated ALP. Two had liver atrophy. Foci of NRH were variably detected in all. Inhomogeneous distribution of other findings included patternless parenchymal fibrous bands, approximation of vascular structures, and commonly, architectural changes of vascular structures. Only bile duct epithelia were unaffected. In addition, small trichrome-positive nodules were found along vein walls or isolated in the parenchyma. Rare foci of non-NRH hepatocytic nodules were noted in 3. Increased CD34 and altered α-SMA IHC expression were variably noted. Periportal ductules and perivenular K7 IHC expression were increased to unpredictable degrees. The extensive but inhomogeneous histopathologic findings in livers of autopsied patients with RVCL-S appear to involve hepatic vascular structures. These findings validate inclusion of vascular liver involvement beyond NRH in this complex hereditary disorder.
Subject(s)
Leukoencephalopathies , Liver Diseases , Vascular Diseases , Male , Humans , Female , Hyperplasia/pathology , Liver/pathology , Leukoencephalopathies/genetics , Leukoencephalopathies/pathology , Vascular Diseases/genetics , Vascular Diseases/pathology , Liver Diseases/genetics , Liver Diseases/pathologyABSTRACT
Children with sickle cell disease (SCD) demonstrate cerebral hemodynamic stress and are at high risk of strokes. We hypothesized that curative hematopoietic stem cell transplant (HSCT) normalizes cerebral hemodynamics in children with SCD compared with pre-transplant baseline. Whole-brain cerebral blood flow (CBF) and oxygen extraction fraction (OEF) were measured by magnetic resonance imaging 1 to 3 months before and 12 to 24 months after HSCT in 10 children with SCD. Three children had prior overt strokes, 5 children had prior silent strokes, and 1 child had abnormal transcranial Doppler ultrasound velocities. CBF and OEF of HSCT recipients were compared with non-SCD control participants and with SCD participants receiving chronic red blood cell transfusion therapy (CRTT) before and after a scheduled transfusion. Seven participants received matched sibling donor HSCT, and 3 participants received 8 out of 8 matched unrelated donor HSCT. All received reduced-intensity preparation and maintained engraftment, free of hemolytic anemia and SCD symptoms. Pre-transplant, CBF (93.5 mL/100 g/min) and OEF (36.8%) were elevated compared with non-SCD control participants, declining significantly 1 to 2 years after HSCT (CBF, 72.7 mL/100 g per minute; P = .004; OEF, 27.0%; P = .002), with post-HSCT CBF and OEF similar to non-SCD control participants. Furthermore, HSCT recipients demonstrated greater reduction in CBF (-19.4 mL/100 g/min) and OEF (-8.1%) after HSCT than children with SCD receiving CRTT after a scheduled transfusion (CBF, -0.9 mL/100 g/min; P = .024; OEF, -3.3%; P = .001). Curative HSCT normalizes whole-brain hemodynamics in children with SCD. This restoration of cerebral oxygen reserve may explain stroke protection after HSCT in this high-risk patient population.
Subject(s)
Anemia, Sickle Cell , Hematopoietic Stem Cell Transplantation , Stroke , Humans , Child , Anemia, Sickle Cell/therapy , Stroke/prevention & control , Hemodynamics , Oxygen , Cerebrovascular CirculationABSTRACT
BACKGROUND: Individuals with sickle cell anemia have heightened risk of stroke and cognitive dysfunction. Given its high prevalence globally, whether sickle cell trait (SCT) is a risk factor for neurological injury has been of interest; however, data have been limited. We hypothesized that young, healthy adults with SCT would show normal cerebrovascular structure and hemodynamic function. METHODS: As a case-control study, young adults with (N=25, cases) and without SCT (N=24, controls) underwent brain magnetic resonance imaging to quantify brain volume, microstructural integrity (fractional anisotropy), silent cerebral infarcts (SCI), intracranial stenosis, and aneurysms. Pseudocontinuous arterial spin labeling and asymmetric spin echo sequences measured cerebral blood flow and oxygen extraction fraction, respectively, from which cerebral metabolic oxygen demand was calculated. Imaging metrics were compared between SCT cases and controls. SCI volume was correlated with baseline characteristics. RESULTS: Compared with controls, adults with SCT demonstrated similar normalized brain volumes (SCT 0.80 versus control 0.81, P=0.41), white matter fractional anisotropy (SCT 0.41 versus control 0.43, P=0.37), cerebral blood flow (SCT 62.04 versus control, 61.16 mL/min/100 g, P=0.67), oxygen extraction fraction (SCT 0.27 versus control 0.27, P=0.31), and cerebral metabolic oxygen demand (SCT 2.71 versus control 2.70 mL/min/100 g, P=0.96). One per cohort had an intracranial aneurysm. None had intracranial stenosis. The SCT cases and controls showed similar prevalence and volume of SCIs; however, in the subset of participants with SCIs, the SCT cases had greater SCI volume versus controls (0.29 versus 0.07 mL, P=0.008). Of baseline characteristics, creatinine was mildly elevated in the SCT cohort (0.9 versus 0.8 mg/dL, P=0.053) and correlated with SCI volume (ρ=0.49, P=0.032). In the SCT cohort, SCI distribution was similar to that of young adults with sickle cell anemia. CONCLUSIONS: Adults with SCT showed normal cerebrovascular structure and hemodynamic function. These findings suggest that healthy individuals with SCT are unlikely to be at increased risk for early or accelerated ischemic brain injury.
Subject(s)
Anemia, Sickle Cell , Sickle Cell Trait , White Matter , Anemia, Sickle Cell/diagnostic imaging , Anemia, Sickle Cell/epidemiology , Case-Control Studies , Cerebral Infarction/diagnostic imaging , Cerebral Infarction/epidemiology , Cerebral Infarction/etiology , Constriction, Pathologic/complications , Humans , Magnetic Resonance Imaging/methods , Oxygen/metabolism , Sickle Cell Trait/diagnostic imaging , Stress, Physiological , Young AdultABSTRACT
Patients with sickle cell anemia (SCA) experience cerebral metabolic stress with an increase in oxygen extraction fraction (OEF) to compensate for reduced oxygen carrying capacity due to anemia. It remains unclear if anemia alone drives this metabolic stress. Using MRI, we collected voxel-wise OEF measurements to test our hypothesis that OEF would be elevated in anemic controls without SCA (AC) compared to healthy controls (HC), but OEF would be even higher in SCA compared to AC. Brain MRIs (N = 159) were obtained in 120 participants (34 HC, 27 AC, 59 SCA). While hemoglobin was lower in AC versus HC (p < 0.001), hemoglobin was not different between AC and SCA cohorts (p = 0.459). Whole brain OEF was higher in AC compared to HC (p < 0.001), but lower compared to SCA (p = 0.001). Whole brain OEF remained significantly higher in SCA compared to HC (p = 0.001) while there was no longer a difference between AC versus HC (p = 0.935) in a multivariate model controlling for age and hemoglobin. OEF peaked within the border zone regions of the brain in both SCA and AC cohorts, but the volume of white matter with regionally elevated OEF in AC was smaller (1.8%) than SCA (58.0%). While infarcts colocalized within regions of elevated OEF, more SCA participants had infarcts than AC (p < 0.001). We conclude that children with SCA experience elevated OEF compared to AC and HC after controlling for the impact of anemia, suggesting that there are other pathophysiologic factors besides anemia contributing to cerebral metabolic stress in children with SCA.
Subject(s)
Anemia, Sickle Cell , Oxygen , Anemia, Sickle Cell/complications , Brain/diagnostic imaging , Child , Humans , Infarction , Stress, PhysiologicalABSTRACT
BACKGROUND: Chronic hypoxia-ischemia is a putative mechanism underlying the development of white matter hyperintensities (WMH) and microstructural disruption in cerebral small vessel disease. WMH fall primarily within deep white matter (WM) watershed regions. We hypothesized that elevated oxygen extraction fraction (OEF), a signature of hypoxia-ischemia, would be detected in the watershed where WMH density is highest. We further hypothesized that OEF would be elevated in regions immediately surrounding WMH, at the leading edge of growth. METHODS: In this cross-sectional study conducted from 2016 to 2019 at an academic medical center in St Louis, MO, participants (age >50) with a range of cerebrovascular risk factors underwent brain magnetic resonance imaging using pseudocontinuous arterial spin labeling, asymmetric spin echo, fluid-attenuated inversion recovery and diffusion tensor imaging to measure cerebral blood flow (CBF), OEF, WMH, and WM integrity, respectively. We defined the physiologic watershed as a region where CBF was below the 10th percentile of mean WM CBF in a young healthy cohort. We conducted linear regression to evaluate the relationship between CBF and OEF with structural and microstructural WM injury defined by fluid-attenuated inversion recovery WMH and diffusion tensor imaging, respectively. We conducted ANOVA to determine if OEF was increased in proximity to WMH lesions. RESULTS: In a cohort of 42 participants (age 50-80), the physiologic watershed region spatially overlapped with regions of highest WMH lesion density. As CBF decreased and OEF increased, WMH density increased. Elevated watershed OEF was associated with greater WMH burden and microstructural disruption, after adjusting for vascular risk factors. In contrast, WM and watershed CBF were not associated with WMH burden or microstructural disruption. Moreover, OEF progressively increased while CBF decreased, in concentric contours approaching WMH lesions. CONCLUSIONS: Chronic hypoxia-ischemia in the watershed region may contribute to cerebral small vessel disease pathogenesis and development of WMH. Watershed OEF may hold promise as an imaging biomarker to identify individuals at risk for cerebral small vessel disease progression.
Subject(s)
Cerebral Small Vessel Diseases , Leukoaraiosis , White Matter , Aged , Aged, 80 and over , Cerebral Small Vessel Diseases/diagnostic imaging , Cerebral Small Vessel Diseases/pathology , Cross-Sectional Studies , Diffusion Tensor Imaging , Humans , Hypoxia/pathology , Middle Aged , Oxygen , Stress, Physiological , White Matter/pathologyABSTRACT
BACKGROUND: Up to 20% of patients with cerebellar infarcts will develop malignant edema and deteriorate clinically. Radiologic measures, such as initial infarct size, aid in identifying individuals at risk. Studies of anterior circulation stroke suggest that mapping early edema formation improves the ability to predict deterioration; however, the kinetics of edema in the posterior fossa have not been well characterized. We hypothesized that faster edema growth within the first hours after acute cerebellar stroke would be an indicator for individuals requiring surgical intervention and those with worse neurological outcomes. METHODS: Consecutive patients admitted to the neurological intensive care unit with acute cerebellar infarction were retrospectively identified. Hypodense regions of infarct and associated edema, "infarct-edema", were delineated by using ABC/2 for all computed tomography (CT) scans up to 14 days from last known well. To examine how rate of infarct-edema growth varied across clinical variables and surgical intervention status, nonlinear and linear mixed-effect models were performed over 2 weeks and 2 days, respectively. In patients with at least two CT scans, multivariable logistic regression examined clinical and radiological predictors of surgical intervention (defined as extraventricular drainage and/or posterior fossa decompression) and poor clinical outcome (discharge to skilled nursing facility, long-term acute care facility, hospice, or morgue). RESULTS: Of 150 patients with acute cerebellar infarction, 38 (25%) received surgical intervention and 45 (30%) had poor clinical outcome. Age, admission National Institutes of Health Stroke Scale (NIHSS) score, and baseline infarct-edema volume did not differ, but bilateral/multiple vascular territory involvement was more frequent (87% vs. 50%, p < 0.001) in the surgical group than that in the medical intervention group. On 410 serial CTs, infarct-edema volume progressed rapidly over the first 2 days, followed by a subsequent plateau. Of 112 patients who presented within two days, infarct-edema growth rate was greater in the surgical group (20.1 ml/day vs. 8.01 ml/day, p = 0.002). Of 67 patients with at least two scans, after adjusting for baseline infarct-edema volume, vascular territory, and NIHSS, infarct-edema growth rate over the first 2 days (odds ratio 2.55; 95% confidence interval 1.40-4.65) was an independent, and the strongest, predictor of surgical intervention. Further, early infarct-edema growth rate predicted poor clinical outcome (odds ratio 2.20; 95% confidence interval 1.30-3.71), independent of baseline infarct-edema volume, brainstem infarct, and NIHSS. CONCLUSIONS: Early infarct-edema growth rate, measured via ABC/2, is a promising biomarker for identifying the need for surgical intervention in patients with acute cerebellar infarction. Additionally, it may be used to facilitate discussions regarding patient prognosis.
Subject(s)
Brain Ischemia , Brain Stem Infarctions , Cerebellar Diseases , Stroke , Edema , Humans , Retrospective Studies , Tomography, X-Ray ComputedABSTRACT
Background and Purpose: Mechanical thrombectomy has dramatically increased patient volumes transferred to comprehensive stroke centers (CSCs), resulting in transfer denials for patients who need higher level of care only available at a CSC. We hypothesized that a distributive stroke network (DSN), triaging low severity acute stroke patients to a primary stroke center (PSC) upon initial telestroke consultation, would safely reduce transfer denials, thereby providing additional volume to treat severe strokes at a CSC. Methods: In 2017, a DSN was implemented, in which mild stroke patients were centrally triaged, via telestroke consultation, to a PSC based upon a simple clinical severity algorithm, while higher acuity/severity strokes were triaged to the CSC. In an observational cohort study, data on acute ischemic stroke patients presenting to regional community hospitals were collected pre- versus post-DSN implementation. Safety outcomes and rate of CSC transfer denials were compared pre-DSN versus post-DSN. Results: The pre-DSN cohort (n=150), triaged to the CSC, had a similar rate of symptomatic intracerebral hemorrhage and discharge location compared with the post-DSN cohort (n=150), triaged to the PSC. Time to stroke unit admission was faster post-DSN (2 hours 40 minutes) versus pre-DSN (3 hours 29 minutes; P<0.001). Transfer denials were reduced post-DSN (3.8%) versus pre-DSN (1.8%; P=0.02), despite an increase in telestroke consultation volume over the same period (median, 3 calls per day pre-DSN versus 5 calls per day post-DSN; P=0.001). No patients who were triaged to the PSC required subsequent transfer to the CSC. Conclusions: A DSN, triaging mild ischemic stroke patients from community hospitals to a PSC, safely reduced transfer denials to the CSC, allowing greater capacity at the CSC to treat higher acuity stroke patients.
Subject(s)
Hospital Distribution Systems , Patient Transfer/methods , Stroke/diagnosis , Stroke/therapy , Triage/methods , Cohort Studies , Female , Hospital Distribution Systems/trends , Humans , Male , Patient Transfer/trends , Pilot Projects , Triage/trendsABSTRACT
OBJECTIVE: To determine the patient- and tissue-based relationships between cerebral hemodynamic and oxygen metabolic stress, microstructural injury, and infarct location in adults with sickle cell disease (SCD). METHODS: Control participants and patients with SCD underwent brain MRI to quantify cerebral blood flow (CBF), oxygen extraction fraction (OEF), mean diffusivity (MD), and fractional anisotropy (FA) within normal-appearing white matter (NAWM) and infarcts on fluid-attenuated inversion recovery. Multivariable linear regression examined the patient- and voxel-based associations between hemodynamic and metabolic stress (defined as elevated CBF and OEF, respectively), white matter microstructure, and infarct location. RESULTS: Of 83 control participants and patients with SCD, adults with SCD demonstrated increased CBF (50.9 vs 38.8 mL/min/100 g, p < 0.001), increased OEF (0.35 vs 0.25, p < 0.001), increased MD (0.76 vs 0.72 × 10-3 mm2s-1, p = 0.005), and decreased FA (0.40 vs 0.42, p = 0.021) within NAWM compared to controls. In multivariable analysis, increased OEF (ß = 0.19, p = 0.035), but not CBF (ß = 0.00, p = 0.340), independently predicted increased MD in the SCD cohort; neither were predictors in controls. On voxel-wise regression, the SCD cohort demonstrated widespread OEF elevation, encompassing deep white matter regions of elevated MD and reduced FA, which spatially extended beyond high-density infarct locations from the SCD cohort. CONCLUSION: Elevated OEF, a putative index of cerebral oxygen metabolic stress, may provide a metric of ischemic vulnerability that could enable individualization of therapeutic strategies in SCD. The patient- and tissue-based relationships between elevated OEF, elevated MD, and cerebral infarcts suggest that oxygen metabolic stress may underlie microstructural injury prior to the development of cerebral infarcts in SCD.
Subject(s)
Anemia, Sickle Cell , White Matter , Adult , Anemia, Sickle Cell/complications , Anemia, Sickle Cell/diagnostic imaging , Cerebral Infarction , Cerebrovascular Circulation , Humans , Magnetic Resonance Imaging , Oxygen , Oxygen Consumption , Stress, Physiological , White Matter/diagnostic imagingABSTRACT
PURPOSE: Sickle cell anemia is a blood disorder that alters the morphology and the oxygen affinity of the red blood cells. Cerebral oxygen extraction fraction measurements using quantitative BOLD contrast have been used for assessing inadequate oxygen delivery and the subsequent risk of ischemic stroke in sickle cell anemia. The BOLD signal in MRI studies relies on Δχdo , the bulk volume susceptibility difference between fully oxygenated and fully deoxygenated blood. Several studies have measured Δχdo for normal hemoglobin A (HbA). However, it is not known whether the value is different for sickle hemoglobin. In this study, Δχdo was measured for both HbA and sickle hemoglobin. METHODS: Six sickle cell anemia patients and 6 controls were recruited. Various blood oxygenation levels were achieved through in vivo manipulations to keep the blood close to its natural state. To account for the differences in oxygen affinity, Hill's equations were used to translate partial pressure of oxygen to oxygen saturation for HbA, sickle hemoglobin, and fetal hemoglobin (HbF) separately. The pH and PCO2 corrections were performed. Temperature and magnetic field drift were controlled for. A multivariate generalized linear mixed model with random participant effect was used. RESULTS: Assuming that Δχdo is similar for HbA and HbF and that ΔχmetHb is 5/4 of Δχdo for HbA, it was found that the Δχdo values for HbA and sickle hemoglobin were not statistically significantly different from each other. CONCLUSION: The same Δχdo value can be used for both types of hemoglobin in quantitative BOLD analysis.
Subject(s)
Hemoglobin A , Hemoglobin, Sickle , Hemoglobins , Humans , Oxygen , OxyhemoglobinsABSTRACT
BACKGROUND AND PURPOSE: Large-scale observational studies of acute ischemic stroke (AIS) promise to reveal mechanisms underlying cerebral ischemia. However, meaningful quantitative phenotypes attainable in large patient populations are needed. We characterize a dynamic metric of AIS instability, defined by change in National Institutes of Health Stroke Scale score (NIHSS) from baseline to 24 hours baseline to 24 hours (NIHSSbaseline - NIHSS24hours = ΔNIHSS6-24h), to examine its relevance to AIS mechanisms and long-term outcomes. METHODS: Patients with NIHSS prospectively recorded within 6 hours after onset and then 24 hours later were enrolled in the GENISIS study (Genetics of Early Neurological Instability After Ischemic Stroke). Stepwise linear regression determined variables that independently influenced ΔNIHSS6-24h. In a subcohort of tPA (alteplase)-treated patients with large vessel occlusion, the influence of early sustained recanalization and hemorrhagic transformation on ΔNIHSS6-24h was examined. Finally, the association of ΔNIHSS6-24h with 90-day favorable outcomes (modified Rankin Scale score 0-2) was assessed. Independent analysis was performed using data from the 2 NINDS-tPA stroke trials (National Institute of Neurological Disorders and Stroke rt-PA). RESULTS: For 2555 patients with AIS, median baseline NIHSS was 9 (interquartile range, 4-16), and median ΔNIHSS6-24h was 2 (interquartile range, 0-5). In a multivariable model, baseline NIHSS, tPA-treatment, age, glucose, site, and systolic blood pressure independently predicted ΔNIHSS6-24h (R2=0.15). In the large vessel occlusion subcohort, early sustained recanalization and hemorrhagic transformation increased the explained variance (R2=0.27), but much of the variance remained unexplained. ΔNIHSS6-24h had a significant and independent association with 90-day favorable outcome. For the subjects in the 2 NINDS-tPA trials, ΔNIHSS3-24h was similarly associated with 90-day outcomes. CONCLUSIONS: The dynamic phenotype, ΔNIHSS6-24h, captures both explained and unexplained mechanisms involved in AIS and is significantly and independently associated with long-term outcomes. Thus, ΔNIHSS6-24h promises to be an easily obtainable and meaningful quantitative phenotype for large-scale genomic studies of AIS.